添加玉米秸秆和根茬对不同肥力黑土微生物残体碳氮的影响

doi:10.3864/j.issn.0578-1752.2023.04.008

摘要/Abstract

摘要：

【目的】作物秸秆和根茬是农田土壤有机质的重要来源之一，经微生物作用以微生物残体形式累积在土壤中，是稳定土壤有机质的重要组成部分。明确不同肥力土壤作物秸秆和根茬还田后微生物残体在土壤中的累积及其对土壤有机碳（SOC）和全氮（TN）的贡献，以期为增加土壤碳氮的库容和稳定性提供依据。【方法】基于黑土长期定位试验站不同肥力水平土壤，利用¹³C¹⁵N双标记方法和氨基糖生物标识物技术，土壤中分别添加玉米秸秆和根茬后进行室内培养，在培养第30天和第180天采样，分析土壤中外源碳（秸秆碳和根茬碳）的残留率、外源氮（秸秆氮和根茬氮）的残留率、微生物残体碳氮的含量及其对土壤有机碳（SOC）和土壤全氮（TN）的贡献率。【结果】培养第180天，秸秆碳和根茬碳在土壤中的平均残留率分别为36.3%和31.7%，秸秆氮和根茬氮的残留率平均分别为95.8%和79.3%。添加秸秆和根茬处理SOC中外源碳含量与TN中外源氮含量的比值（¹³C-SOC/¹⁵N-TN）在培养第180天平均分别为17.6和28.5，与培养第30天相比平均分别下降了47.9%和28.2%。培养期间，高肥土壤真菌残体碳氮含量是低肥土壤的1.17倍左右，细菌残体碳氮含量是低肥土壤的1.31倍。第180天，添加秸秆处理土壤微生物残体（真菌和细菌）碳和氮含量平均比添加根茬处理增加了8.5%左右。培养结束后（第180天），真菌残体碳对高肥和低肥土壤SOC的贡献率平均分别为37.0%和33.8%，细菌残体碳的贡献率平均分别为11.2%和9.2%；添加秸秆和根茬的处理真菌残体碳对SOC的贡献率平均分别为36.0%和34.7%，细菌残体碳的贡献率平均分别为10.8%和9.6%。第30天，真菌残体氮和细菌残体氮对TN的贡献率平均分别为55.2%和16.3%；培养第180天，真菌残体氮对低肥和高肥土壤TN的贡献率平均分别为63.5%和60.5%，细菌残体氮的贡献率平均分别为16.4%和17.5%。培养180天与初始土壤相比，细菌残体碳和氮对高肥土壤SOC和TN的贡献率平均分别增加了4.8%和7.4%，对低肥土壤平均分别增加了20.3%和32.5%。【结论】真菌残体对土壤有机碳库的稳定和氮库的扩容起着重要的作用。添加玉米秸秆较根茬更有利于微生物残体碳氮在土壤中的累积。低肥土壤添加秸秆和根茬有利于细菌残体碳和氮向土壤有机碳库和氮库的转化。

关键词: 玉米秸秆, 玉米根茬, 土壤微生物残体, 氨基糖, 土壤有机碳, 土壤全氮, 黑土

Abstract:

【Objective】 Maize shoot and root residues are the significance sources of soil organic matter (SOM). Exogenous carbon (C) and nitrogen (N) are assimilated by soil microorganism, accumulated as microbial necromass and contributed to relatively stable SOM. The objectives of this study were to clarify the accumulation of microbial residue C and N in different fertility levels of soil with shoot and root residues addition, and to qualify the contributions of microbial residue C and N to soil organic C (SOC) and total N (TN), respectively, so as to provide a basis for increasing the storage and stability of SOC and TN. 【Method】 Based on a long-term experiment of black soil with different fertility levels, this study used the ¹³C¹⁵N isotope labeling and amino sugar biomarkers methods, and mixed the labeled maize shoot and root residues with black soil samples. Then the mixture samples were incubated in lab, and sampled in 30 and 180 days. The percentages of exogenous C (shoot C and root C) and N (shoot N and root N) remaining in soil, contents of microbial residues C and N, and their contributions to SOC and TN were analyzed. 【Result】On the 180th day, the percentages of shoot C and root C remaining in soil were, on average, 36.3% and 31.7%, respectively, and those of shoot N and root N remaining in soil were, on average, 95.8% and 79.3%, respectively. On the 180th day, the ratio of the SOC derived from exogenous C (¹³C-SOC) to TN derived from exogenous N (¹⁵N-TN) were, on average, 17.6 and 28.5 in the soils with shoot and root residue addition, respectively. The ratio of ¹³C-SOC to ¹⁵N-TN was decreased by 47.9% and 28.2% in the soils with shoot and root residue addition on the 180th day compared with the 30th day, respectively. During the incubation, the contents of fungal and bacterial residue in the high fertility soil were, on average, 1.17 and 1.31 times those in the low fertility soil, respectively. On the 180th day, the content of microbial residue C and N (fungal and bacterial) was, on average, 8.5% higher in the soil added with shoot than that in the soil added with root. On the end of incubation, the average percentage of fungal residue C contributed to SOC was 37.0% and 33.8%, respectively, and that of bacterial residue C contributed to SOC was 11.2% and 9.2% in the high and low fertility level soils, respectively. The average percentage of fungal residue C contributed to SOC was 36.0% and 34.7%, and that of bacterial residual C contributed to SOC was 10.8% and 9.6% on the end of incubation, respectively. The average percentage of bacterial residue C contributed to SOC was 55.2% and 16.3% in the soil added with shoot and root on the 30th day, respectively. The average percentage of fungal residue N contributed to TN was 63.5% and 60.5%, and that of bacterial residue N to TN was 16.4% and 17.5% in low and high fertility level soils on the 180th day, respectively. The percentage of bacterial residue C and N contributed to SOC and TN was increased by 4.8% and 7.4% in the high fertility soil and by 20.3% and 32.5% in low fertility soil on the 180th day compared with the basic soil without shoot and root addition, respectively. 【Conclusion】 The accumulation of fungal residue was of great significance for the storage and stability of SOC and TN. Maize shoot addition promoted the accumulation of microbial residues C and N in soil compared with root addition. Low fertility soil with the addition of shoot and root improved the transformation of bacterial residue C and N to SOC and TN.

Key words: maize shoot, maize root, soil microbial residue, amino sugar, soil organic carbon, soil total nitrogen, black soil

马南, 安婷婷, 张久明, 汪景宽. 添加玉米秸秆和根茬对不同肥力黑土微生物残体碳氮的影响[J]. 中国农业科学, 2023, 56(4): 686-696.

MA Nan, AN TingTing, ZHANG JiuMing, WANG JingKuan. Effects of Maize Shoot and Root Residues Added on Microbial Residue Carbon and Nitrogen in Different Fertility Levels of Black Soil[J]. Scientia Agricultura Sinica, 2023, 56(4): 686-696.

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指标 Index	高肥土壤 High fertility level of soil	低肥土壤 Low fertility level of soil
有机碳Soil organic carbon (g·kg^-1)	18.0	16.7
全氮Total nitrogen (g·kg^-1)	1.75	1.53
碳氮比 Ratio of soil organic carbon to total nitrogen	10.3	11.0
δ¹³C值δ¹³C value (‰)	-21.7	-21.5
δ¹⁵N值δ¹⁵N value (‰)	8.49	7.92
真菌残体碳Fungal residue carbon (mg·kg^-1)	6354	5698
细菌残体碳Bacterial residue carbon (mg·kg^-1)	1913	1275
真菌残体氮Fungal residue nitrogen (mg·kg^-1)	988	886
细菌残体氮Bacterial residue nitrogen (mg·kg^-1)	284	189
真菌残体碳与SOC比值Ratio of fungal residue carbon to SOC (%)	35.3	34.1
细菌残体碳与SOC比值Ratio of bacterial residue carbon to SOC (%)	10.6	7.64
真菌残体氮与TN比值Ratio of fungal residue nitrogen to TN (%)	56.4	16.3
细菌残体氮与TN比值Ratio of bacterial residue nitrogen to TN (%)	57.9	12.4

处理 Treatment	外源碳对土壤有机碳的贡献率 Contribution percentage of exogenous carbon to total soil organic carbon (%)		外源氮对土壤全氮的贡献率 Contribution percentage of exogenous nitrogen to total soil nitrogen (%)
处理 Treatment	30 d	180 d	30 d	180 d
HF+R	17.9±0.115 A	15.0±0.437 ab	5.5±0.593 A	6.1±0.362 a
HF+S	23.0±0.416 C	14.4±0.974 a	8.7±0.239 C	8.0±0.269 b
LF+R	20.9±0.549 B	15.1±0.141 ab	7.3±0.353 B	5.7±0.003 a
LF+S	26.0±0.316 D	16.3±0.021 b	9.6±0.020 C	10.4±0.113 c
外源有机物类型 Types of exogenous organic matter (p)	178^**	0.370^ns	55.5^**	197^**
土壤肥力水平 Soil fertility level (s)	60.0^**	3.42^ns	14.1^*	18.0^*
外源有机物类型×土壤肥力水平 p×s	0.001^ns	2.65^ns	1.19^ns	37.2^**

处理 Treatment	土壤有机碳与全氮的比值 Ratio of SOC to TN		土壤有机碳中外源碳含量与全氮中外源氮含量比值 Ratio of ¹³C-SOC to ¹⁵N-TN
处理 Treatment	30 d	180 d	30 d	180 d
HF+R	11.7±0.461 A	10.9±0.129 ab	38.3±2.79 AB	25.1±1.46 b
HF+S	11.9±0.254 A	10.2±0.073 a	31.7±1.456 A	18.5±1.22 a
LF+R	14.3±0.231 B	12.1±0.251 c	41.0±2.49 B	32.0±0.665 c
LF+S	13.5±0.103B	11.4±0.423 bc	36.5±0.640 AB	16.7±1.92 a
外源有机物类型 Types of exogenous organic matter (p)	0.855^ns	6.44^*	7.50^*	62.3^**
土壤肥力水平 Soil fertility level (s)	54.0^**	22.6^**	3.53^ns	3.40^ns
外源有机物类型×土壤肥力水平 p×s	2.82^ns	0.022^ns	0.254^ns	9.96^*